JUPITER, Fla. — Jorge Posada started a new chapter in his baseball life Monday as he began working for the Marlins.

Yankees South keeps growing day by day.

In CEO Derek Jeter and Posada, a special adviser, half of the Core Four are Marlins. Sure, New Yorkers going to Miami is nothing new, but Jeter’s Yankees Crew is impressive in Year 2 as he continues to change the losing culture in every way possible from the ground up.

For example: Watch the Marlins leave the practice fields at the Roger Dean Stadium complex. They don’t walk off. They hustle off, running to the clubhouse, especially this week with Captain’s Camp underway for the top prospects as well as the full camp opening Monday.

Jeter called in January and Posada accepted the challenge.

“I’m so excited to do this. I live in Miami, the kids are getting older, my son is 18 and in college, my daughter is 16, everything worked out perfectly,’’ Posada told The Post as he made his way to Field 2. “It’s about helping the catchers, helping in the minor leagues, the Latin speaking kids, there’s a lot of things I am looking forward to doing. This organization is moving forward.’’

Posada, 47, checks off a lot of boxes, including a championship mentality. It’s strange seeing Posada, a five-time All-Star and five-time Silver Slugger, in Marlins colors, but once he started working with the catchers, he was right at home.

Jorge Posada and catching coach Brian Schneider.AP

What does he want to bring to his new job?

“Just the way it was when I was playing, winning is the most important thing,’’ said Posada, who won four rings over his 17-year career with the Yankees. “You compete, you want to always go out there and win the ballgame, you want to be in that frame of mind that somebody is always watching.’’

Those are Yankee principles Jeter and Posada learned under the Boss, George Steinbrenner.

They have their work cut out for them with the Marlins, but how can you bet against these two? Winning was the core of their baseball experience in pinstripes.

Posada recently spoke for 40 minutes to the Marlins’ top young players.

“Hopefully they can grasp something out of that, they are not going to grasp everything, but hopefully something clicks,’’ Posada said. “It helped me when I heard Reggie Jackson talk in 1991. So just keep being there for them.’’

What about the Yankees? Was Posada offered a role with them?

“There was nothing official,’’ he said. “They just wanted me to be a guest coach.’’

Was that disappointing?

“Not really,’’ Posada said as he spread out his hands as if to say what can you do. “It is what it is. I’m OK.’’

Jorge Posada is better than OK and, who knows, he might check off the boxes as a manager in the minors or in Miami some day, though he said managing is not in his plans. He wants to be helpful to Marlins manager Don Mattingly.

Jorge Posada and Derek JeterAP

Jeter made it clear why he wanted Posada to help tutor the young Marlins.

“Jorge has lived in Miami for years and everybody knows how close we are,’’ Jeter said. “He wanted to get back in the game. This was an avenue for him to do it at his own pace. He’s going to add a lot of value, he’s going to add a lot of value to our player development system. I’m coming from an organization that valued ex-players I was always a sponge for knowledge when I was younger and we want to bring that same vibe to this organization.’’

Noted Marlins’ president of baseball operations Michael Hill, “I would say you check all of the above boxes with Jorge, because we’re going to use him every way possible to impact our organization.”

It all comes back to winning, Jeter said.

“We had a particular mindset when we were coming up through our organization. Mr. Steinbrenner expected you to win every game you played. He didn’t care if you were in the minor leagues or the major leagues; it was a mentality. I think we grew up with that environment, and we can share those experiences with the players.”